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VMS4007 > Population Biology > Flashcards

Population Biology Flashcards

1
Q

The extinction process can be broken down into which 2 paradigms ?

A

Declining population paradigm & Small population paradigm

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2
Q

Describe the declining population paradigm

A
  • Habitat destrution
  • habiotat degradation
  • Habitat fragmentation
  • Over-hunting & live capture
    Pollution
  • Invasive species
  • Major dx outbreaks
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3
Q

Describe the small population paradigm

A

“the effets of smallness”
-> factors causing extinction under this:
- Environmental stochasticity
- Catastrophes
- Demographic stochasticity
- Genetic deterioration

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4
Q

Define environmental stochasticity:

A

random unpredictable variation in environmental factors such as temp and rainfall

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5
Q

Define demogrpahic stochasticity

A

Random unpredictable variation in sex ratios, and births ad death rates

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6
Q

Define Catastrophes:

A

extreme environemental events such as disease epidemics ro hurricanes

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7
Q

Define Genetic stochasticity

A

Inbreeding depression, loss of genetic diversity and the accumulation of deleterious mutations

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8
Q

What does stable age distribution demographic look like

A

an age pyramid with more births and young animals than old

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9
Q

Demographic stochasticity will reflect events due to chance alone aka:

A
  • Births, Deaths, sexr ratio at birth
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10
Q

Does demographic stochasticity have a larger impact on larger or smaller populations?

A

smaller

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11
Q

Define genetic diversity

A

The variety of alleles & gnotypes present in the group under study

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12
Q

How is genetic diversity observed?

A
  • Polymorphism
  • Allelic diversity
  • Average heterozygosity (expected & observed)
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13
Q

Allelic diversity & heterozygosity what is it?

A
  • Different forms of an allele for a particule trait (A,b, c, d which become Ab, Bc, Cd and this is heterozygosity)
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14
Q

What is Expected heterozygosity also known as?

A

Gene Diversity

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15
Q

What is expected heterozygosity?

A

Proportion of animals int he population expected to be heterozygous if random breeding takes place

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16
Q

T/ F The ability of a population to evolve depends on allelic heterozygosity and the rate at which it does depends on expected heterozygosity

A

True

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17
Q

IF a population had Hardy-Weinberg equilibrium what heterozygosity would we have?

A

The Mean heterozygosity

18
Q

What are the greatest determinants of genetic change in small vs large populations?

A

Large -> natural selection
Small -> chance

19
Q

What is the most important factor when looking at impat of genetic drift?

A

Effective population size Ne

20
Q

Wha is the effective population ?

A

The breeding population with viable offspring / portion that passes its genes into next generation

21
Q

Ne definition

A

Number of individuals that would result in the same loss of genetic diversituy, inbreeding or genetic drift if they behaved int he manner of an iealized population

22
Q

What is an idealized population?

A

A conceptual mating population with equal numbers of hermaphrodite individuals breeding in each generation, and Poisson variation in family sizes

23
Q

What are the assumptions in an idealized population?

A
  • No fluctuations in population size from generation to generation
  • Discere (non-overlapping) generations
  • Hermaphrdite individuals
  • Random mating
24
Q

What is Ne>50 mean?

A

short term - to avoid the immediate deleterious effects of inbreeding

25
Q

What is Ne>500?

A

Long term - to allow new mutations to restore heterozygosity and additive genetic variation as rapidlu as it is lost by genetic drift

26
Q

What is currently thought to be the value of Ne minimul?

A

Ne = 1000 or even 50000 to avoid loss fo diversity through drift

27
Q

What are the ffects of genetic drift ?

A
  1. Alleles are lost (both adaptive, & maladaptive)
  2. Drift causes loss of genetic diversity & fixation of alleles within populations
28
Q

What is Loss of diversity inversely proportional to?

A

Ne

29
Q

The effects of Sampling in every generation are ….

A

cumulative

30
Q

When do population bottlenecks happen?

A

When populations unergo susbstantial contraction
- Catastrophes
- Hbpitat loss
- Population fragmentation

When individuals in wild migrate to form new populations

When individuals from the wild are caught to form captive populations

When wild - to -wild translcoations take place

When reintroductions take place

31
Q

TRUE OR FALSE. - Populations that have gone through bottlenecks have lower genetic diversity than those that have not

A

TRUE

32
Q

What is the effect of management interventions?

A

Can cause bottlenecks

33
Q

What does Inbreeding cause ?

A
  • Inc in homozygozity & dec in heterozygosity
  • Inc in chance of expression of recessive deleterious alleles in phenotype
34
Q

How do we measure inbreeding?

A

Inbreeding coefficient (F) which is the probability that two alleles are identical by descent

35
Q

describe effects of inbreeding depression?

A
  • Inc juvenile mortality
  • Reduced longevity
  • Reduced reproduction
  • Inc susceptibility to disease
36
Q

T/F inbreeding increases the risk of extinction

A

Inbreeding inc the risk of extinction - True

37
Q

Give 3 examples fo species that have experienced populations decline & extinction as a result of inbreeding

A

Bighorn sheep
Florida panthers
Adders

38
Q

What effects of outbreeding depression caused by crosses between different sub-species or species?

A

Offspring maladapted to both environments

39
Q

Can inbreeding and outbreeding depression occur simultaneously?

A

Yes (ex: Arabian oryx)

40
Q

What is heterosis ?

A

(hybrid vigor) - improved fitness of hybrids

41
Q

describe the extinction vortex

A
  • The adverse interaction between human
    impacts, inbreeding & demographic
    fluctuation that results in a feedback loop
    that spirals towards extinction

VMS4007 (4 decks)

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